Secondary Compression of Peat with or without Surcharging

Laboratory Investigation of the Pre- and Post-Cyclic Volume Change Properties of Sherman Island Peat

“…Fox and Edil (1992) showed that the secondary compression index c α is not constant but increases with time. Mesri et al (1997) suggest a range of 0.05 to 0.07 for C α /C c .…”

“…Volume change characteristics of peaty organic soil have been investigated by Dhowian and Edil (1980), Fox and Edil (1992), Mesri et al, (1997), and Mesri and Ajlouni (2007), among others. These studies mostly focus on measurement of consolidation parameters (e.g., virgin compression index, coefficient of consolidation) and secondary compression parameters.…”

Effect of salt grain additions on fibrous peat consolidation

“…013, respectively, were marginally greater than corresponding values for peat specimen P2(u)/76/20/1; where e 0 is the initial void ratio and˜e the change in void ratio for a particular load stage and time period t. An apparent tertiary compression evident in the end portion of the strain curve for peat specimen P2(u)/76/40/17 was largely absent for salt-treated specimen P2(fs)/76/40/8 (Figure 4(a)). Tertiary compression is generally associated with strain ensuing from some decomposition of the peat solids occurring over the course of experimental laboratory testing (Mesri et al, 1997). It is postulated that the salt treatment may have changed the salinity of the peat specimen, possibly creating a less favourable environment for microbial decomposition to occur and therefore a more stable creep rate under loading.…”

“…Preloading/surcharging in combination with vertical drains is the most widely applied technique used to improve the geomechanical properties of peat and other organic soil deposits (Mesri and Ajlouni, 2007;Mesri et al, 1997;Santagata et al, 2008). However, several investigators (Lake, 1961(Lake, , 1963McNulty, 1991;Mesri and Ajlouni, 2007) have suggested that vertical (sand) drains have little effect in accelerating the settlement rate for fibrous peat, considering the peat's high initial permeability and dominant creep effects.…”

Remote Monitoring of a Model Levee Constructed on Soft Peaty Organic Soil

“…High secondary compression is inferred from the rapid settlement rate following dissipation of pore pressures to preconstruction levels after 10 days. High secondary compression is a common feature of peat soil that is well documented in the literature (e.g., Mesri and Ajlouni 2007), and is usually attributed to high void ratio of peat, high ratios of the index of secondary compression to the compression index (C α /C c ), and high initial permeability of the peat (Mesri et al 1997) . In laboratory oedometer tests performed on piston samples retrieved from the site (Shafiee et al, 2013), distinguishing primary consolidation from secondary compression using Casagrande's (1938) procedure was difficult due to the high c α .…”